The present invention relates to a parking brake for vehicles, of the type that comprises a drum and at least one shoe intended to press against a cylindrical surface formed on the inside of the drum.
In vehicles fitted with disc brakes on the rear wheels, it is part of the prior art to provide each disc brake with a drum-type parking brake comprising a drum and at least one shoe intended to be pressed against said drum when the so-called handbrake is operated.
It is also known that in order to ensure that the user can park the vehicle satisfactorily, even on the very first occasion on which the handbrake is operated, the brake has to be xe2x80x9cworn inxe2x80x9d at the time of manufacture of the vehicle by putting the vehicle, which may in particular be an industrial vehicle, truck or the like, through repeated braking cycles, i.e. a specific wearing-in of the brake. This procedure obviously adds to the cost.
It has been suggested that the cylindrical surface formed on the inside of the drum be coated with a layer of chromium. This solution enables the wearing-in process to be dispensed with but is unattractive from a cost point of view because it means extra work at the drum processing stage, the drum having to undergo a complex and expensive extra process owing in part to the necessity of protecting with suitable coatings those parts of the component that are not to be chrome-plated.
The starting point of the present invention is the problem of devising a parking brake whose structural and functional characteristics are such as to overcome the abovementioned disadvantages.
This problem is solved by a parking brake of the specified type, which is characterized by the fact that it comprises surface irregularities formed in the cylindrical surface.